Silhouette safety control for paint spray conveyor



April 11, 1967 R. F. WIGGINS SILHOUETTE SAFETY CONTROL FOR PAINT SPRAYCONVEYOR Filed April 29, 1964 rill I llll'lllnlll'llllvllllllllllalllll.

. pill/I47 EEEE a E rw ATTORNEYS United States Patent 3,313,402SILHOUETTE SAFETY CONTRGL FOR PAINT SPRAY CONVEYOR Richard F. Wiggins,Fairfield, Conn, assignor to The Gyrornat Corporation, Fairfield, Comp,a corporation of Connecticut Filed Apr. 29, 1964, Ser. No. 363,495 3Claims. (Cl. 198232) The present invention relates to spray paintingsystems, and more particularly, to :a safety control or interlock for aconveyorized automated spray painting system.

In the spray painting or spray treating of an article on an automatedbasis, the article is typically conveyed past a spray source such as anozzle or an array of nozzles where it is subjected to a spraytreatment. It is often of prime, if not critical, importance that thearticle be in the proper orientation in relation to the spray source, toinsure that it is adequately and properly treated by the spray material.An improper orientation of the article may result in an imperfection inthe sprayed article, necessitating its scrapping or re-treating and thussubtantialy increasing production costs.

Accordingly, it is an object of the present invention to provide ahighly simplified, yet wholly effective safety control system for aconveyor which all automatically shut down the conveyor or provide awarning when an article to be spray painted is not properly oriented atit approaches a spray treatment station. More specifically, it is anobject to provide an interlock for a conveyor carrying suspendedconductive or partially conductive articles through an electrostatic orother spray painting station.

In accordance with an important aspect of the invention, a silhouette ofthe desired orientation of the article to be sprayed is formed by aplurality of electric probes interposed in the path of the conveyedarticle. The probes are associated with a safety control relay in theenergizing circuitry of the conveyor and are adapted to stop theconveyor through the opening of the safety relay when any one of theprobes is contacted, in any degree, by the article, indicating that thearticle is misoriented. A properly oriented article will pass throughthe silhouette formed by the probes without any contact and withoutcausing the disruption of the conveyor operation.

For a more complete understandin g of the invention and its attendantadvantages, reference should be made to the following detaileddescription taken in conjunction with the accompanying drawing showin aschematic representation of the new and improved safety interlock for aconveyorized spray painting system.

in accordance with the invention, an overhead conveyor comprising an Irail 11 with a movable trolley 12 supported thereon, travels in apredetermined path in an automated painting process through anorientation control station A and a spray painting station B. As shown,the trolley 12 includes wheels 13 and an article hook 1 from which aconductive or partially conductive article 15 may be suspended. As aspecific aspect of the invention, the aforementioned conveyor elementsare electrical conductors in order that electrical continuity orconductivity between the article 15 and the rail 11 may be establishedand maintained.

The spray station B is provided with sources, such as nozzles 52 (showngreatly enlarged), arranged to apply a coating to the article when it isin a predetermined, desired orientation 16 (shown in phantom) therewith.

In accordance with an important aspect of the invention, at a point inthe conveyor path in advance of the spray station B, the orientationcontrol station A is estabiished by one or more, usualy a series, ofprobes 17 arranged so that their tips 18 generally outline thededfildfifiz Patented Apr. 1.1, 1967 sired, predetermined orientation16. The probes are advantageously fabricated from short lengths of pianowire, for example, and are sup-ported in cantilever fashion by opposedwalls 19, 2d of a suitable dielectric material. The relationship of thestations A and B is, of course, such that the probe elements aremaintained free from contamination by sprayed paint.

The safety interlock of the present invention acts to de-energize theconveyor motor 25 and thus halts the conveyor when an article isdetected to be improperly oriented by the probes 17. Typical controlcircuitry for the interlock system generally includes conveyor motorenergizing circuitry (starting and stopping) and a safety interlockcricuit associated therewith to de-energize the mortor and/ or to soundan alarm, if desired, when a misoriented article contacts one of theprobes 17.

More specifically, the energizing circuitry includes a primary powersource S, which is connected by conductors 23, 24 to the conveyor motor25. The conductor 23 include-s a pair of relay contacts 26, which arenormally open but are closable upon actuation of a two-pole motoroperating relay 29.

The motor starting circuitry includes a normally open starting switch30, advantageously a pushbutton type switch. One side of the start ngswitch is connected through a conductor 33 to the conductor 23 at oneside of the source S, and the other side is connected through aconductor 34 to the energizing coil of the operating relay 29, the otherside of the coil being connected to the condoctor 24 at the other sideof the source.

The motor stopping circuitry includes a conductor 36 connected acrossthe starting switch, between the conductors 33, 34. The conductor 26includes three pairs of contacts 37, 39, 41; a pair of normally opensafety switch contacts 37 which is held closed in normal operation byenergization of a safety control relay 43; a pair of normally closed,stop button contacts 39; and a pair of contacts 41, holding contactswhich are normally open but are closable upon energization of theoperating relay 29.

The safety interlock circuitry includes the aforementioned safetycontrol relay 43, whose energizing coil is connected across the outputterminals of an amplifier 48, whose sensitivity is such that it can beadjusted even through relatively highly resistive materials. Inaccordance with the invention, the input to the amplifier is in thenature of a safety control pulse or signal which is created by thecontacting, no matter how slight, of a misoriented conductive orpartially conductive article by one of the probes 17. The article itselfmay be electrically connected to ground through the hook 14, the trolley12, the rail 11, and a ground conductor 59, as shown in the drawing,although in some instances it need not be grounded if it has a largeenough mass effect. As shown, the probes 17 are connected to one of theamplifier input terminals by a conductor 49. The other amplifier inputterminal is connected to ground through a power source S by a conductor51.

Operation of the new and improved system is initiated by momentarydepression of the start button 30, which will energize the operatingrelay 29, closing the contacts and energizing the conveyor drive motor25. After momentary closure of the start switch 30, the relay 29 remainsenergized through a holding circuit, including its now closed contacts41. The coil of the operating relay will remain energized, maintainingthe operation of the conveyor mot-or, until the current thereto isinterrupted by the manual depression of the stop button 39 or by theopening of the contacts 37 through energization of the safety controlrelay 43. De-energization of the operating relay 29 by either of thesealternatives will open the motor energizing circuit, as will beunderstood, and will leave the motor circuit open until the relay 29 isonce 3 again energized through the depression of the starting button 30.

The safety control pulse necessary to energize the control relay 43 iscreated by the closing of an orientation switch (indicated generally at58), the contacts of which are normally open and which include, as aspecific aspect of the invention, the wire probes 17 and the conductivearticle 15, itself. If the article is not hanging properly as it passesthrough the control station A, one of the probes 17 will be contacted,momentarily closing an orientation switch and immediately closing downthe system. Since the articles contemplated by the invention may be oflight weight and since they are freely suspended, switches of thetypical positive action or position displacement types would not besuitable for use as or in lieu of an orientation switch, because atypical misoriented part would possess insufiicient inertia to actuatesuch a conventional switch reliably. Therefore, the importance of theuse of the electroconductive article 15, itself, the amplifier 48, andthe conductive conveyor elements 11-14 as integral elements of theelectrical interlock system should be well understood.

It will be appreciated that the simplified and unique system of thepresent invention, provides a high degree of safety control for a spraypaint system in which proper orientation of the article being painted isimportant to the ultimate success of the process. Moreover, utilizationof simple wire probes in combination with an amplifier and theconductive conveyor elements to create an effective safety control pulseprovides a very inexpensive, yet extremely reliable and efiicient,safety control for the system.

In a typical system, the wire probes 17 may be one or more in number andadjustably mounted for inward and outward movement. Thus, parts ofvarious configurations may be accommodated by the control system.

Although the present invention has been described with reference to aspecific preferred embodiment, it should be understood that thedescription has been made by way of example, and that certain changes indetails of construction and arrangement of the elements may be madewithout departing from the scope of the invention as hereinafterclaimed.

1 claim:

1. Safety control for a spray painting system, compris- (a) conveyormeans adapted to transport a suspended electroconductive article havinga predetermined, desired outline and orientation in a predetermined P(b) a spray painting station located at a point in said path,

(c) an orientation control station located in said path in advance ofsaid spray painting station,

(d) said control station having an array of wire-like probe elementsgenerally defining said predetermined outline,

(e) first electrical circuit means energizing said conveyor means,

(f) amplification means in association with said conveyor means and saidprobe elements, and

(g) second electrical circuit means normally open but being closableupon contact of an improperly oriented article with one of said probes,and

(h) interlock relay means associated with said amplifier and said firstcircuit means and adapted to deenergize said conveyor means uponcompletion of said second circuit means.

2. Safety control for a spray painting system, compris- (a) conveyormeans adapted to transport a suspended electroconductive article havinga predetermined, desired outline and orientation in a predeterminedpath,

(b) a spray painting station located at a point in said path,

(c) an orientation control station located in said path in advance ofsaid spray painting station,

(d) said control station having an array of wire-like probe elementsgenerally defining said predetermined outline;

(e) first electrical circuit means including a control switch,

(f) amplification means in association with said first electricalcircuit means and said probe elements, and

(g) second electrical circuit means normally open but being closableupon contact of an improperly oriented article with one of said probes,and

(h) interlock relay means associated with said amplifier and said firstcircuit means and adapted to change the condition of said control switchupon completion of said second circuit means.

3. Safety control for a spray painting system, compris- (a) conveyormeans adapted to transport a suspended electroconductive article havinga predetermined, desired outline and orientation in a predeterminedpath,

(b) a spray painting station located at a point in said path,

(c) an orientation control station located in said path in advance ofsaid spray painting station,

((1) said control station having an array of wire-like probe elementsgenerally defining said predetermined outline,

(e) first electrical circuit means including a control switch,

(f) interlock relay means in association with said first electricalcircuit means and said probe elements, and

(g) second electrical circuit means normally open but being closableupon contact of an improperly oriented article with one of said probes,and

(h) said interlock relay means being adapted to change the condition ofsaid control switch upon completion of said second circuit means.

References Cited by the Examiner UNITED STATES PATENTS 1,350,774 8/1920Braley 198232 1,368,583 2/1921 Thompson .198232 1,803,689 5/1931 Bernadt198-37 3,129,807 4/1964 Richter 198232 FOREIGN PATENTS 550,355 10/1956Italy.

EVON C. BLUNK, Primary Examiner.

EDWARD A. SROKA, Examiner.

1. SAFETY CONTROL FOR A SPRAY PAINTING SYSTEM, COMPRISING (A) CONVEYORMEANS ADAPTED TO TRANSPORT A SUSPENDED ELECTROCONDUCTIVE ARTICLE HAVINGA PREDETERMINED, DESIRED OUTLINE AND ORIENTATION IN A PREDETERMINEDPATH, (B) A SPRAY PAINTING STATION LOCATED AT A POINT IN SAID PATH, (C)AN ORIENTATION CONTROL STATION LOCATED IN SAID PATH IN ADVANCE OF SAIDSPRAY PAINTING STATION, (D) SAID CONTROL STATION HAVING AN ARRAY OFWIRE-LIKE PROBE ELEMENTS GENERALLY DEFINING SAID PREDETERMINED OUTLINE,(E) FIRST ELECTRICAL CIRCUIT MEANS ENERGIZING SAID CONVEYOR MEANS, (F)AMPLIFICATION MEANS IN ASSOCIATION WITH SAID CONVEYOR MEANS AND SAIDPROBE ELEMENTS, AND (G) SECOND ELECTRICAL CIRCUIT MEANS NORMALLY OPENBUT BEING CLOSABLE UPON CONTACT OF AN IMPROPERLY ORIENTED ARTICLE WITHONE OF SAID PROBES, AND (H) INTERLOCK RELAY MEANS ASSOCIATED WITH SAIDAMPLIFIER AND SAID FIRST CIRCUIT MEANS AND ADAPTED TO DEENERGIZE SAIDCONVEYOR MEANS UPON COMPLETION OF SAID SECOND CIRCUIT MEANS.